Ultrasonic blade with static casing

Abstract

An ultrasonic surgical device capable of cutting biological tissues such as bone and cartilage. The ultrasonic surgical device includes a static casing, which sheaths an ultrasonic horn, and a lubrication film, which separates the ultrasonic horn and the static casing. The static casing, which may also incorporate a plurality of fluid channels to allow passage of fluids along its length and eventual distribution of such fluids at the cutting end and biological tissue interface, inhibits the transfer of heat generated along the ultrasonic horn. The cutting end and the static casing are separated by a flexible joint, which serves to inhibit the transfer of vibrational energy, and consequently heat, from the cutting end to the static casing. As such, the static casing remains stable and can be used both to manipulate the surgical device with greater haptic control and facilitate effective penetration of larger cross-sections of biological tissue.

What is claimed is: 
     
       1. An ultrasonic bone cutting device, comprising:
 a housing, said housing containing a source of ultrasonic vibrations; 
 an ultrasonic horn, said ultrasonic horn having a first end, an elongated main body, and a second end, said first end coupled to said source of ultrasonic vibrations, said second end coupled to a cutting end, said cutting end comprising a top planar surface and an opposing bottom planar surface, a distal continuous blade edge without interrupting openings connecting the top planar surface to the bottom planar surface; 
 a static casing formed from a rigid biocompatible material, said static casing having an attachment end, an opposite end, and a sheathing slot, said attachment end configured to be coupled to said housing, said sheathing slot extending the length of said static casing, said sheathing slot sheathing a length of said elongated main body, said static casing having a height and a width profile equal to a height and a width profile of said cutting end; 
 a solid lubrication film adhered to at least one of an external surface of the elongated main body and an internal surface of the sheathing slot, said solid lubrication film separating said sheathing slot from said elongated main body; and 
 a flexible joint formed from a viscoelastic material, said flexible joint positioned between said opposite end of said static casing and a proximal end of said cutting end, said flexible joint having a height and a width profile equal to the height and the width profile of said cutting end, said flexible joint defining a passage extending therethrough, said passage substantially aligned with said sheathing slot, a portion of said elongated main body passing through said passage; 
 whereby said lubrication film reduces generation of heat between said sheathing slot and said elongated main body, said static casing configured to reduce transfer of heat generated by the ultrasonic vibrations along the length of said elongated main body to neighboring biological tissues, said flexible joint reduces transfer of the ultrasonic vibrations from said cutting end to said static casing, the equal height and width profiles of said static casing, said flexible joint, and said cutting end configured to facilitate effective penetration into and cutting of large cross-sections of biological tissue. 
 
     
     
       2. The ultrasonic bone cutting device of  claim 1  wherein said blade edge is configured for ablating. 
     
     
       3. The ultrasonic bone cutting device of  claim 1  wherein said blade edge is configured for abrading. 
     
     
       4. The ultrasonic bone cutting device of  claim 1  wherein said blade edge comprises a plurality of serrations. 
     
     
       5. The ultrasonic bone cutting device of  claim 1  wherein a portion of an outer surface of at least one of said static casing and said cutting end is coated with a solid lubrication film.